"Plant in ericaceous compost" not specific enough!

I have an azalea 'snow pearl' to plant and I have some ericaceous compost, but being new to this game, I need to know how much ericaceous compost I need to put beneath and around this shrub. Please enlighten me!

Just plant it in a pot using the ericaceous compost, the same as you would plant any other plant

If it's going in the ground, dig the hole, chuck a few spadefuls of the compost in the hole and some on the soil around, mix a bit with your spade, put the plant in the hole and fill in with the compost/soil mix and firm it in and water it well, it should be fine.

Calculate in your mind how far you think the plant is going to spread and make sure you use ericaceous compost in the hole you dig. Is it going to grow into a big plant, or is is a rockery azalea? Or is it in a pot?

First, we need to establish whether the soil in your garden is acidic enough for your azaela to thrive. As you are 'new to this game' there are two things we can do to find out the suitability of your soil. You could look around other gardens in your area, speak to locals who have nice gardens and therefore would (hopefully) be knowledgeable....when you look around you should look to see if there are other azaelas growing locally in the soil or other plants that like an acidic soil eg rhododendrons, camellias.

The other thing you could do is purchase a ph soil testing kit from local garden centre or DIY store. They shouldn't be very expensive nor difficult to understand.

If we find that your soil is suitable then follow the tips already given. If however your soil is unsuitable then you will have to keep your plant in a pot inorder for it to do well. In which case you will fill the pot with only ericaecous compost. Hope this helps, come back if it doesn't.....or you have further questions